This invention relates generally to cooling systems.
A data center may be defined as a location, e.g., room, that houses computer systems arranged in a number of racks. A standard rack may be defined as an Electronics Industry Association (EIA) enclosure, 78 in. (2 meters) wide, 24 in. (0.61 meter) wide and 30 in. (0.76 meter) deep. Standard racks may be configured to house a number of computer systems, e.g., about forty (40) systems, with future configurations of racks being designed to accommodate up to eighty (80) systems. The computer systems typically include a number of components, e.g., one or more of printed circuit boards (PCBs), mass storage devices, power supplies, processors, micro-controllers, semi-conductor devices, and the like, that may dissipate relatively significant amounts of heat during the operation of the respective components. For example, a typical computer system comprising multiple microprocessors may dissipate approximately 250 W of power. Thus, a rack containing forty (40) computer systems of this type may dissipate approximately 10 KW of power.
The power required to transfer the heat dissipated by the components in the racks to the cool air contained in the data center is generally equal to about 10 percent of the power needed to operate the components. However, the power required to remove the heat dissipated by a plurality of racks in a data center is generally equal to about 50 percent of the power needed to operate the components in the racks. The disparity in the amount of power required to dissipate the various heat loads between racks and data centers stems from, for example, the additional thermodynamic work needed in the data center to cool the air. In one respect, racks are typically cooled with fans that operate to move cooling fluid, e.g., air, cooling fluid, etc., across the heat dissipating components; whereas, data centers often implement reverse power cycles to cool heated return air. The additional work required to achieve the temperature reduction, in addition to the work associated with moving the cooling fluid in the data center and the condenser, often add up to the 50 percent power requirement. As such, the cooling of data centers presents problems in addition to those faced with the cooling of the racks.
Conventional data centers are typically cooled by operation of one or more air conditioning units. For example, compressors of air conditioning units typically require a minimum of about thirty (30) percent of the required operating energy to sufficiently cool the data centers. The other components, e.g., condensers, air movers (fans), etc., typically require an additional twenty (20) percent of the required cooling capacity. As an example, a high density data center with 100 racks, each rack having a maximum power dissipation of 10 KW, generally requires 1 MW of cooling capacity. Air conditioning units with a capacity of 1 MW of heat removal generally requires a minimum of 300 KW input compressor power in addition to the power needed to drive the air moving devices, e.g., fans, blowers, etc. Conventional data center air conditioning units do not vary their cooling fluid output based on the distributed needs of the data center. Instead, these air conditioning units generally operate at or near a maximum compressor power even when the heat load is reduced inside the data center.
The substantially continuous operation of the air conditioning units is generally designed to operate according to a worst-case scenario. For example, air conditioning systems are typically designed around the maximum capacity and redundancies are utilized so that the data center may remain on-line on a substantially continual basis. However, the computer systems in the data center may only utilize around 30-50% of the maximum cooling capacity. In this respect, conventional cooling systems often attempt to cool components that may not be operating at a level which may cause their temperatures to exceed a predetermined temperature range. Consequently, conventional cooling systems often incur greater amounts of operating expenses than may be necessary to sufficiently cool the heat generating components contained in the racks of data centers.
Moreover, the future of data center cooling will involve many small (1,000 to 2,000 sq. ft.) and readily deployable data centers that are akin to portable buildings or shipping containers. Current cooling systems, such as chilled water units, are relatively time-consuming to install and difficult to use in such compact data centers.
According to one embodiment, the present invention pertains to a method for cooling a room configured to house a plurality of computer systems. In the method there is provided a plurality of evaporator units that are distributed in parallel and that are configured to receive air from the room and to deliver air to the room. The plurality of evaporator units are supplied with refrigerant that is operable to cool the air received from the room. In addition, temperatures are sensed at one or more locations in the room and the temperature of the air is controlled in response to the sensed temperatures at the one or more locations.
According to another embodiment, the invention relates to a system for cooling a room containing a plurality of computer systems. The system includes a plurality of evaporator units that are distributed in parallel and that are configured to receive refrigerant through a refrigerant line and to receive air. The air may be cooled through heat transfer with the refrigerant, and the plurality of evaporator units have at least one fan that is configured to cause air to flow out of the plurality of evaporator units. An evaporator controller is operable to control a supply of the refrigerant to the plurality of evaporator units and is operable to control the speed of the at least one fan. A refrigeration system is provided for cooling the refrigerant, and a refrigeration system controller is configured to operate the refrigeration system to vary the temperature of the refrigerant.
According to yet another embodiment, the present invention pertains to a system for cooling computer systems housed in one or more racks maintained in a room. The system includes means for cooling air including means for receiving cooling fluid. The system also includes means for delivering cooled air to the computer systems and means for measuring temperatures at one or more locations in the room. Additionally, the system includes means for controlling delivery of the cooled air in response to the means for measuring, and a means for controlling the temperature of the cooling fluid.
According to still another embodiment, the present invention pertains to computer readable storage medium on which is embedded one or more computer programs that implement a method of cooling a room configured to house a plurality of computer systems. The one or more computer programs include a set of instructions for providing a plurality of evaporator units that are distributed in parallel and that are configured to receive air from the room and to deliver air to the room. The plurality of evaporator units are supplied with refrigerant that is operable to cool the air received from the room. In addition, temperatures are sensed at one or more locations in the room and the temperature of air is controlled in response to the sensed temperatures at the one or more locations.